ESDU 07003 presents a semi-empirical investigation of the viscous drag coefficient of wing geometries in the absence of a body. The effects of cranks@ section geometry and spanwise variations of camber and geometric twist on wing viscous drag coefficient are all investigated. Strip theory has been used to obtain equations from which wing viscous drag coefficient may be predicted. These equations are applicable to those wing geometries and values of lift coefficient where both upper and lower surface boundary layers are fully attached@ and there are no shock waves present.